A skeleton map is a diagram visually representing an analysis result by text mining. The skeleton map is a diagram representing the relationship between words and the strength of the relationship in document information that is an analysis target. For example, a technology related to a skeleton map is discussed in Japanese Laid-open Patent Publication No. 2004-21913. In addition, a technology related to display of document information that is an analysis target is discussed in Japanese Laid-open Patent Publication No. 2007-252609.